Fix Microsoft 365 Emails Rejected by Gmail Accounts
Question details
Users are unable to send emails from a Microsoft 365 work account with a custom domain to Gmail recipients due to server rejections.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Sending outbound emails from a corporate Microsoft 365 account to any Gmail address.
- Observed behavior
- Every email sent to a Gmail account is rejected, returning a bounce message or Non-Delivery Report (NDR) to the sender.
Locate and save the complete bounce message or Non-Delivery Report (NDR) you received from Gmail, as it contains essential diagnostic error codes needed to resolve the issue.
Contact Your IT Administrator to Verify Domain Authentication
Because this issue involves a custom domain on a Microsoft 365 work account, administrative access is required to modify DNS records and authorize sending servers.
Gmail enforces strict sender authentication policies to prevent spam and phishing. If your company's Microsoft 365 custom domain lacks properly configured SPF, DKIM, or DMARC records, Gmail will automatically reject your outgoing messages.
As an end user, you cannot fix this directly. You must escalate the issue to your global or tenant administrator so they can update the domain's DNS settings.
Open the rejection email you received from Gmail. Copy the entire contents of the bounce message, especially any error codes (e.g., 550 5.7.1 or 550 5.7.26).
Open a support ticket or send a message to your Microsoft 365 global administrator, email administrator, or IT support team, pasting the complete NDR.
Explicitly ask your administrator to verify the domain's SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) records, and configure DMARC if necessary.
Ask the admin to run a message trace in the Exchange Admin Center to identify whether the rejection stems from IP reputation, content filters, or sending limits.
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Frequently Asked Questions
Why is Gmail rejecting my Microsoft 365 work emails?
Gmail rejects emails from custom domains primarily when the domain lacks valid authentication records (SPF, DKIM, and DMARC). This is a security measure enforced by Google to block unauthorized senders and spam.
What is an NDR and why does my administrator need it?
An NDR (Non-Delivery Report) is the automated bounce email you receive when message delivery fails. It contains specific diagnostic codes that allow your IT administrator to pinpoint the exact reason Google's servers rejected the message.
Can I fix the SPF or DKIM records myself?
No. Updating SPF, DKIM, and DMARC records requires administrative access to your domain's DNS hosting provider and the Microsoft 365 admin center. Only your IT or tenant administrator can make these changes.
